A confrontation develops between a group of associates, resulting in one of the men being restrained by his lapels, circa 1929. (Photo by Hulton Archive/Getty Images)

American actor George Chakiris holds a switchblade open, ready to fight a rival gang in a still from the musical film, “West Side Story”, directed by Jerome Robbins and Robert Wise, 1961. (Photo by United Artists/Courtesy of Getty Images)

An armed soldier attacks a protestor on Bloody Sunday when British Paratroopers shot dead 13 civilians on a civil rights march in Derry City, on 30th January 1972. (Photo by Frederick Hoare/Central Press/Getty Images)

A teenage street gang carry out a mugging in a deserted alley in New York City, circa 1955. (Photo by Carl Purcell/Three Lions/Getty Images)

Members of a teenage girl gang convincing an unwilling recruit to join the gang, circa 1955. (Photo by Vecchio/Three Lions/Getty Images)

A man steps in to break up a brawl between Edna Nolan and her husband's girlfriend, on 13th March 1954. (Photo by Bert Hardy/Picture Post/Getty Images)

Two members of a teenage New York street gang threaten another member who wants to leave, circa 1955. (Photo by Carl Purcell/Three Lions/Getty Images)

A young man is attacked as he flees the taunts of a pursuing mob following a Ku Klux Klan rally May 31, 2003 in west suburban Chicago town of Berwyn, Illinois. (Photo by Scott Olson/Getty Images)

People beat up another man during clashes of Pro-Russian and Pro-Ukrainian activists during a rally in Sevastopol, Crimea, Ukraine, 09 March 2014. The USA and European Union have threatened sanctions against Moscow over the military standoff in the strategic Crimean peninsula, and are urging Russia to pull back its forces in the region and allow in international observers and human rights monitors. Crimea, which has a majority ethnic Russian population, is strategically important to Russia as the home port of its Black Sea Fleet. (Photo by EPA/STR)